Overview

Lesson Procedure

70-75 minutes of class time across 5 phases.

1. Warm-Up10 minutes
2. Direct Instruction20 minutes
3. Guided Practice15 minutes
4. Independent Practice15-20 minutes
5. Closure10 minutes

1. Warm-Up10 minutes

   Project an advertisement line with its footnote and ask what the footnote does to the claim.

   Warm-Up Prompt

   "Ad: 'All-day battery.*' Footnote: '*Up to 18 hours of video playback at 50% brightness with wireless off, in company testing.' What distinction does the footnote draw that the headline does not? Name one thing a buyer would want to know that neither line tells you."

   The ad is invented for this warm-up. Students should see the distinction between "all day" in general use and one test condition (video, half brightness, wireless off), and at least one gap: no figure for ordinary mixed use, no number of devices tested, no sense of how the battery ages. Tell students that RST.11-12.1 asks them to read every science and technical text this way: cite the evidence, and attend to the distinctions the author makes and to the gaps or inconsistencies in the account.

2. Direct Instruction20 minutes

   Part 1: Distinctions, gaps and inconsistencies. An important distinction is a line the author draws that the argument depends on: between two terms, two cases, a rule and its exception, or what is known and what is believed. A gap is something the account needs but does not supply; an author may acknowledge it or miss it. An inconsistency is two parts of the account that do not agree, such as a summary and the data it summarizes. Every claim about any of these must be supported with quoted words.

   What to look for, and the evidence that proves it

   Feature	Signals in the text	Evidence to cite
   Distinction between terms	"I use the term ...," "in a ... sense," "not ... but ..."	The definition and the contrast it sets up
   Degree of certainty	"I believe," "probably," "may be trusted," "it is just possible"	The qualifier, and the claim it limits
   Rule and exception	"generally," "in many cases," "except," "but"	Both the rule and the exception
   Acknowledged gap	"unknown," "no one can say," "we did not test"	The admission, and what it leaves open
   Unacknowledged gap	A conclusion wider than the method: one sample, one condition	The claim and the part of the method that cannot support it
   Inconsistency	A summary, total or trend that differs from the data	Both statements, quoted side by side

   Part 2: Model with Darwin. Explain that On the Origin of Species (1859) presents Darwin's theory that species change over time by natural selection. In Chapter III he stops to define a key term. Read the excerpt aloud, then work through the examples. Use Diagram 1 with examples 2 and 3.

   I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture. A plant which annually produces a thousand seeds, of which on an average only one comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The missletoe is dependent on the apple and a few other trees, but can only in a far-fetched sense be said to struggle with these trees, for if too many of these parasites grow on the same tree, it will languish and die. But several seedling missletoes, growing close together on the same branch, may more truly be said to struggle with each other. As the missletoe is disseminated by birds, its existence depends on birds; and it may metaphorically be said to struggle with other fruit-bearing plants, in order to tempt birds to devour and thus disseminate its seeds rather than those of other plants. In these several senses, which pass into each other, I use for convenience sake the general term of struggle for existence.

   • Distinction by definition

     What does Darwin include in "Struggle for Existence" that the everyday meaning of the phrase leaves out?

     Result: He uses the term "in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny." Two distinctions are cited: struggle includes dependence, not only fighting, and it counts offspring, not only survival. The parenthesis ranks them: leaving progeny is "more important."

   • Distinction in degree: literal and figurative

     How does Darwin separate the two dogs from the desert plant?

     Result: The dogs "in a time of dearth, may be truly said to struggle with each other." The desert plant "is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture." The qualifiers "truly" and "more properly" mark the line between a real contest and a dependence the word only stretches to cover (Diagram 1).

   • Tracking qualifiers across a series

     Does Darwin treat all the mistletoe cases the same way?

     Result: No. The mistletoe "can only in a far-fetched sense be said to struggle with" the trees it lives on, but "several seedling missletoes, growing close together on the same branch, may more truly be said to struggle with each other." Same plant, two cases, two degrees. A summary that says "Darwin says mistletoe struggles with trees" drops the qualifier and misreports him.

   • A limit the author admits

     Does Darwin claim his senses of "struggle" are sharply separate?

     Result: No: "In these several senses, which pass into each other, I use for convenience sake the general term of struggle for existence." He admits the senses blur together and that the single term is a convenience. A careful reader therefore asks, for any later claim about struggle, which sense is meant.

3. Guided Practice15 minutes

   Pairs read the sexual selection excerpt from Chapter IV. They highlight distinctions in one color, qualifiers of certainty in a second and anything the account leaves out in a third. Then each pair writes two sentences: one on the distinction between sexual selection and natural selection, one on a gap. Circulate and push for exact evidence: "Darwin says sexual selection is different" is a start; quoting both halves of "the result is not death to the unsuccessful competitor, but few or no offspring" is evidence.

   Sexual Selection.—Inasmuch as peculiarities often appear under domestication in one sex and become hereditarily attached to that sex, the same fact probably occurs under nature, and if so, natural selection will be able to modify one sex in its functional relations to the other sex, or in relation to wholly different habits of life in the two sexes, as is sometimes the case with insects. And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases, victory will depend not on general vigour, but on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving offspring. Sexual selection by always allowing the victor to breed might surely give indomitable courage, length to the spur, and strength to the wing to strike in the spurred leg, as well as the brutal cock-fighter, who knows well that he can improve his breed by careful selection of the best cocks.

   Debrief with one question: The paragraph begins "Inasmuch as peculiarities often appear under domestication in one sex ... the same fact probably occurs under nature, and if so ..." What does "probably" and "if so" tell you about the evidence for the rest of the argument? Students should see that Darwin reasons from domestic breeds to nature and marks the step as likely, not shown. Activity 3 then compares the excerpt with later evidence.

   For Activity 2 (Report Audit). The lab report below was written for this page, with invented data and deliberate flaws.

   1Summary. We tested whether salt water lowers the germination of radish seeds. Salt clearly prevents radish seeds from germinating: germination fell steadily as the salt concentration rose.

   2Method. We lined four Petri dishes with paper towel and placed 25 radish seeds in each. We moistened each dish with 10 mL of sodium chloride solution at 0, 25, 50 or 100 mM (millimoles per liter); the 0 mM dish received distilled water. The dishes were kept on the lab shelf at room temperature for 5 days, except the 100 mM dish, which was placed on the windowsill because the shelf was full. A seed counted as germinated when its root was at least 2 mm long. We checked the dishes each day and added 2 mL of the same solution whenever the paper towel looked dry.

   3Results (invented data for this page). Germinated seeds after 5 days, out of 25 in each dish: 0 mM, 23 seeds (92%); 25 mM, 22 seeds (88%); 50 mM, 24 seeds (96%); 100 mM, 14 seeds (56%). In total, 81 of the 100 seeds germinated.

   4Conclusion. Because germination was lowest in the strongest salt solution, salt water is harmful to all crop plants, and farmers should never irrigate with water that contains salt.

4. Independent Practice15-20 minutes

   Students answer quiz questions 1-14 on the Darwin excerpt from Chapter IX and questions 15-20 on the test memo that follows it. Paragraph numbers are printed beside both texts. In the Darwin excerpt, "C. oenas" is Columba oenas, the stock dove, a wild pigeon of Europe; the fantail and pouter are domestic pigeon breeds.

   1The main cause, however, of innumerable intermediate links not now occurring everywhere throughout nature depends on the very process of natural selection, through which new varieties continually take the places of and exterminate their parent-forms. But just in proportion as this process of extermination has acted on an enormous scale, so must the number of intermediate varieties, which have formerly existed on the earth, be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection which can be urged against my theory. The explanation lies, as I believe, in the extreme imperfection of the geological record.

   2In the first place it should always be borne in mind what sort of intermediate forms must, on my theory, have formerly existed. I have found it difficult, when looking at any two species, to avoid picturing to myself, forms directly intermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons have both descended from the rock-pigeon; if we possessed all the intermediate varieties which have ever existed, we should have an extremely close series between both and the rock-pigeon; but we should have no varieties directly intermediate between the fantail and pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified, that if we had no historical or indirect evidence regarding their origin, it would not have been possible to have determined from a mere comparison of their structure with that of the rock-pigeon, whether they had descended from this species or from some other allied species, such as C. oenas.

   3So with natural species, if we look to forms very distinct, for instance to the horse and tapir, we have no reason to suppose that links ever existed directly intermediate between them, but between each and an unknown common parent. The common parent will have had in its whole organisation much general resemblance to the tapir and to the horse; but in some points of structure may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases, we should be unable to recognise the parent-form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links.

   4It is just possible by my theory, that one of two living forms might have descended from the other; for instance, a horse from a tapir; and in this case direct intermediate links will have existed between them. But such a case would imply that one form had remained for a very long period unaltered, whilst its descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; for in all cases the new and improved forms of life will tend to supplant the old and unimproved forms.

   1Summary. The TR-500 keeps drinks cold for 24 hours. In our test, the bottle held its contents at or below 5 °C for the full 24 hours, which supports the "24 hours cold" label.

   2Method. We tested one TR-500 bottle (500 mL) in two runs, on different days, in the same room at 22 °C. For run A, we filled it with 250 g of ice and 250 mL of water. For run B, we filled it with 500 mL of tap water chilled to 4.0 °C, with no ice. The lid was opened only to take readings. Every 6 hours, a probe thermometer (accurate to 0.2 °C) was placed in the center of the liquid; each reading took less than 10 seconds. In this memo, "cold" means 5 °C or below.

   3Results (invented data for this page). Run A: 0.2 °C at the start, 0.3 °C at 6 hours, 0.4 °C at 12 hours, 0.6 °C at 18 hours and 0.9 °C at 24 hours; ice was still floating at 24 hours. Run B: 4.0 °C at the start, 7.5 °C at 6 hours, 10.1 °C at 12 hours, 12.5 °C at 18 hours and 14.3 °C at 24 hours.

   4Discussion. Both runs show that the insulation works: the contents warmed far more slowly than a glass of water would on a table. Run A proves that the label is accurate. We did not test the bottle with the lid opened often during the day, in a warm room or car, or with more than one bottle.

5. Closure10 minutes

   Exit ticket: "From any passage today, quote one distinction the author makes and one gap or inconsistency. For each, write one sentence on why a reader who missed it would misunderstand the text." Sort the tickets by whether the gap was one the author admits or one the student found.

   Teacher note on the 1859 text. Darwin's words are quoted exactly, including his spellings ("missletoe," "organisation"). Some of his framing is dated. The sexual selection excerpt describes females as something males struggle for "possession" of, and it cites the "brutal cock-fighter" as a breeder who knows his craft; cockfighting is now illegal throughout the United States. Say this plainly in discussion. The science also needs a modern note after the quiz: since 1859 many transitional fossils have been found, such as Archaeopteryx (first described in 1861) and the fossil series of early whales and horses, though the record is still incomplete. Mendel's work on inheritance (1866) was not known to Darwin; modern genetics now explains several of the patterns in the homework passage.

   Homework passage. The homework uses Darwin's paragraph on inheritance from Chapter I. Students look at how he separates what is unknown from what he thinks "may be trusted."

   The laws governing inheritance are quite unknown; no one can say why the same peculiarity in different individuals of the same species, and in individuals of different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characters to its grandfather or grandmother or other much more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes or to one sex alone, more commonly but not exclusively to the like sex. It is a fact of some little importance to us, that peculiarities appearing in the males of our domestic breeds are often transmitted either exclusively, or in a much greater degree, to males alone. A much more important rule, which I think may be trusted, is that, at whatever period of life a peculiarity first appears, it tends to appear in the offspring at a corresponding age, though sometimes earlier. In many cases this could not be otherwise: thus the inherited peculiarities in the horns of cattle could appear only in the offspring when nearly mature; peculiarities in the silkworm are known to appear at the corresponding caterpillar or cocoon stage. But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that when there is no apparent reason why a peculiarity should appear at any particular age, yet that it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   In paragraph 1, what does Darwin call "perhaps, ... the most obvious and gravest objection which can be urged against my theory"?

   AThat natural selection works too slowly to be observed BThat living species cannot be arranged into groups CThat geology does not reveal a finely graduated chain of intermediate forms DThat the earth is too young for species to change

2. Question 2 of 20 · Multiple Choice

   What explanation does Darwin give in paragraph 1 for the missing links?

   AThe extreme imperfection of the geological record BIntermediate varieties never existed CFossils of intermediate forms have been destroyed by collectors DThe intermediate forms lived only in the sea

3. Question 3 of 20 · Multiple Choice

   Why, according to paragraph 1, must the number of intermediate varieties that once existed be "truly enormous"?

   ABecause every species is intermediate between two others BBecause the process of extermination by natural selection has acted on an enormous scale CBecause the geological record shows a great many of them DBecause intermediate varieties live longer than the forms they connect

4. Question 4 of 20 · Multiple Choice

   In paragraph 2, which view does Darwin call "wholly false"?

   AThat species have a common but unknown progenitor BThat pigeon breeds descended from the rock-pigeon CThat the progenitor differed from its descendants DThat the missing forms were directly intermediate between two living species

5. Question 5 of 20 · Multiple Choice

   According to paragraph 2, where should we look for intermediate forms?

   ABetween each species and a common but unknown progenitor BBetween any two living species that look alike COnly among domestic breeds DIn the oldest rocks only

6. Question 6 of 20 · Multiple Choice

   In the pigeon illustration, which form would a complete series of intermediate varieties NOT contain?

   AA variety between the fantail and the rock-pigeon BA variety combining a tail somewhat expanded with a crop somewhat enlarged CA variety between the pouter and the rock-pigeon DA variety with a tail somewhat expanded and a crop like the rock-pigeon's

7. Question 7 of 20 · Multiple Choice

   According to paragraph 2, what would we be unable to decide about the fantail and pouter if we had "no historical or indirect evidence" of their origin?

   AWhether they are pigeons at all BWhether they could interbreed CWhether they came from the rock-pigeon or from some other allied species DWhether they are older than the rock-pigeon

8. Question 8 of 20 · Multiple Choice

   What does paragraph 3 say about the common parent of the horse and the tapir?

   AIt was directly intermediate between them BIt must have looked exactly like a tapir CIt is known from fossils DIn some points of structure it may have differed from both more than they differ from each other

9. Question 9 of 20 · Multiple Choice

   Paragraph 3 ends: we could not recognize the parent-form "unless at the same time we had a nearly perfect chain of the intermediate links." What does this condition admit?

   AThat identifying ancestors requires the very evidence that paragraph 1 says the record lacks BThat the parent-forms have all been found CThat the horse is descended from the tapir DThat comparing structures is enough to identify an ancestor

10. Question 10 of 20 · Multiple Choice

    In paragraph 4, when would direct intermediate links have existed between two living forms?

    AWhen the two forms look very different BWhen one of the two living forms descended from the other CWhen both forms live in the same country DWhen the geological record is complete

11. Question 11 of 20 · Multiple Choice

    Why does Darwin expect the case in paragraph 4 to be "a very rare event"?

    ABecause tapirs are rare animals BBecause horses and tapirs cannot interbreed CBecause it needs one form to stay unaltered for a very long period while its descendants change, and new forms tend to supplant old ones DBecause the geological record is imperfect

12. Question 12 of 20 · Short Answer

    Explain the distinction Darwin draws in paragraph 2 about which intermediate forms we should expect to have existed, using his pigeon illustration. Then explain why this distinction matters to the objection in paragraph 1. Cite the text.

    Show model answer

13. Question 13 of 20 · Short Answer

    Darwin introduces his explanation for the missing links in paragraph 1 with the words "as I believe." Using only this excerpt, evaluate how well that explanation is supported. What does the excerpt give as support, and what gap remains?

    Show model answer

14. Question 14 of 20 · Short Answer

    Paragraph 2 calls the habit of picturing directly intermediate forms "a wholly false view," but paragraph 4 says it is "just possible" that direct intermediate links existed between two living forms. Is this an inconsistency in Darwin's account? Argue your answer with quotations.

    Show model answer

15. Question 15 of 20 · Multiple Choice

    In the test memo, what distinction does the Method draw between run A and run B?

    ARun A used a different bottle from run B BRun A started with ice in the water; run B started with chilled water and no ice CRun A was tested in a warm car; run B was tested in a room DRun A was measured every hour; run B every 6 hours

16. Question 16 of 20 · Multiple Choice

    The Summary says the bottle "held its contents at or below 5 °C for the full 24 hours." Which result contradicts it?

    ARun A was 0.9 °C at 24 hours BIce was still floating in run A at 24 hours CRun B was 7.5 °C at 6 hours DRun B started at 4.0 °C

17. Question 17 of 20 · Multiple Choice

    Which statement in the Discussion is NOT supported by any data in the memo?

    ARun A stayed at or below 5 °C for 24 hours BRun B warmed to 14.3 °C by 24 hours CThe bottle was not tested in a warm car DThe contents warmed "far more slowly than a glass of water would on a table"

18. Question 18 of 20 · Multiple Choice

    Which limitation does the memo itself acknowledge?

    AOnly one bottle was tested BThe thermometer's accuracy is not stated CThe memo does not define "cold" DThe runs were on different days, so their room temperatures may have differed

19. Question 19 of 20 · Short Answer

    Rewrite the memo's Summary in two or three sentences so that it is consistent with the Results and keeps the memo's own distinction between the runs and its definition of "cold." Cite the numbers you use.

    Show model answer

20. Question 20 of 20 · Short Answer

    The Discussion concludes: "Run A proves that the label is accurate." Identify two problems with this conclusion, one an inconsistency or overstatement and one a gap in the method, and say what additional test would address the gap.

    Show model answer

These standards connect to RST.11-12.1: prerequisites to review first, parallel standards at the same level, and next steps that build on it.

Standard text: Common Core State Standards for English Language Arts & Literacy. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.